1. Field of the Invention
The present invention relates to a folder-type mobile communication device; more particularly, the present invention relates to a folder-type mobile communication device with a band-stop circuit capable of reducing the influence of a system ground plane on its built-in antenna.
2. Description of the Related Art
In recent years, with the fast development of mobile communication technology, mobile communication devices have become essential and irreplaceable in daily life. With the incremental increases in demands for digital audio/video functions, the screen size of the mobile communication device is getting bigger. Therefore, the application development is not only focused on bar-type mobile communication devices, but also on folder-type mobile communication devices.
Because the system ground plane of a bar-type mobile phone antenna is significantly different from that of a folder-type mobile phone antenna, there is generally a need to design different types of antennas, so as to make both the folder-type mobile phone and the bar-type mobile phone respectively meet the requirements of a specific communication system standard. If the bar-type mobile phone antenna is directly used as the folder-type mobile phone antenna, the overall efficiency of the mobile phone antenna will be lowered due to the change of the system ground plane.
U.S. Pat. No. 7,199,762 B2 (Wireless device with distributed load) discloses a technique for improving the influence on a mobile communication device antenna caused by the change of a system ground plane. It discloses that both capacitive coupling and inductive coupling are generated between two system ground planes of a folder-type mobile communication device at the same time. However, the above function can only be achieved by means of utilizing two connection devices to connect to two system ground planes, which invariably increases the complexity of the overall design of the folder-type mobile communication device, as well as increasing its manufacturing cost.
Therefore, there is a need to provide a folder-type mobile communication device to mitigate and/or obviate the aforementioned problems.